You could write it off as a fluke in February. When it happened again in March, people got concerned. Now stocks are tumbling a third time in 2018, and investors are starting to sense something has changed.

<p>Sears is planning to close up to 150 of its department and discount stores and keep at least 300 open as part of a plan to restructure under U.S. bankruptcy protection, people familiar with the matter said Friday.</p>